Optical elements in which polarizing elements having different polarization orientations are disposed in each small region and electronic devices in which such optical elements are integrated are commercialized around a display device and a measuring device. For example, Xpol (registered trademark) manufactured by Arisawa Manufacturing Co., Ltd. is sold as a display device.
As disclosed in JP-A-2004-309868, an imaging device is known which includes: imaging means in which pixels corresponding to an integer multiple of a predetermined number of scanning lines are formed on an imaging surface; first horizontal component polarizing means that transmits only horizontal components of first video light from a subject; and first vertical component polarizing means that is disposed at a position separated by a predetermined distance from the first horizontal component polarizing means so as to transmit only vertical components of second video light from the subject. In the imaging device, horizontal components having passed through the first horizontal component polarizing means are collected by a predetermined range of pixels on the imaging surface, and vertical components having passed through the first vertical component polarizing means are collected by a remaining range of pixels excluding the predetermined range. Horizontal and vertical component polarization filters disposed at a position separated by a predetermined distance in relation to the imaging surface of a CCD so as to be separated by a distance corresponding to a parallax of a person are formed together with two lenses.
As disclosed in JP-A-2008-216956, a polarizing element is known which includes: a substrate that is transparent to light in a used band; a reflecting layer in which strip-shaped thins film extending uniaxially are arranged on the substrate in a one-dimensional grid shape at a pitch smaller than the wavelength of light in the used band; a dielectric layer formed on the reflecting layer; and an inorganic microparticle layer having a light absorbing effect, in which inorganic microparticles are arranged on the dielectric layer at positions corresponding to the strip-shaped thin films in a one-dimensional grid shape. The polarizing element employs a so-called wire grid polarizer technique.
Moreover, as disclosed in 34th Optics Symposium (2009), Lecture 16 “Application of Polarization Imaging to SiC Wafer Defect Evaluation”, a technique is known in which polarizing elements having a plurality of polarization orientations are disposed on a solid-state imaging element commonly called a CCD (Charge Coupled Device) element or a CMOS (Complementary Metal Oxide Semiconductor) image sensor, whereby a plurality of polarization information items are spatially divided and acquired at the same time. Specifically, a polarization camera system is proposed in which incident light to the solid-state imaging element is split into polarized light components of four polarization orientations by a photonic crystal array, and the intensities of the respective polarization orientations are output at the same time, whereby polarization analysis which was conventionally performed by time-division processing is concurrently realized by spatial-division processing, so that polarized images can be output without using a driving portion. However, since the photonic crystal array is manufactured separately from the solid-state imaging element and both are integrated by bonding, it is difficult to apply such a technique to an imaging device having a small pixel size.
In general, a wire grid polarizer has a 1-dimensional or 2-dimensional grid structure formed of a conductor material. As shown by a conceptual diagram in FIG. 35, when the formation pitch P0 of the wire grid is significantly smaller than the wavelength of an incident electromagnetic wave, the electromagnetic wave vibrating on a plane parallel to the extension direction of the wire grid is selectively reflected or absorbed by the wire grid. Therefore, as shown in FIG. 35, although the electromagnetic wave arriving at the wire grid polarizer includes a vertically polarized light component and a horizontally polarized light component, the electromagnetic wave having passed through the wire grid polarizer becomes linearly polarized light in which a vertically polarized light component is dominant. Here, focusing on a visible wavelength band, when the formation pitch P0 of the wire grid is equal to or shorter than the wavelength of the electromagnetic wave incident to the wire grid polarizer, polarized light components biased from the plane parallel to the extension direction of the wire grid are reflected or absorbed by the front surface of the wire grid. On the other hand, when the electromagnetic wave having the polarized light components biased from the plane vertical to the extension direction of the wire grid is incident to the wire grid, the electric field having propagated through the front surface of the wire grid exits from the rear surface of the wire grid in a state of having the same wavelength as the incident wavelength and the same polarization orientation. The above physical phenomenon is known and the details thereof are disclosed, for example, in New Technology and New Communications, Tsuruta “3. Pencil of light” Chapter 23, Grid Polarizer.